Malignant Epithelioid Hemangioendothelioma

John Walter Millstine, MD - Case Coordinator
Russell Chapman Wilson, MD - Radiology Discussion
Jonathan H Lin, MD, PhD - Pathology Discussion
Piran Aliabadi, MD - Attending Radiologist
Carl S Winalski, MD - Attending Radiologist
Steven E Seltzer, MD - Attending Radiologist
Pablo R Ros, MD, MPH - Attending Radiologist

June 24, 2002

Presentation

Imaging Findings

A zoomed-in radiograph of the proximal right tibia and fibula demonstrates periostial reaction involving the lateral cortex of the proximal tibia and the medial cortex of the proximal fibula. There is no bony destruction evident and no apparent soft tissue mass. The periostial reaction seems fairly benign and does not appear to be an acute development.

A T1-weighted coronal magnetic resonance (MR) image of the proximal tibia and fibula shows irregular T1 hyperintense mass posterior to the tibia. Peripheral ring enhancement is visible inferiorly. The mass is hyperintense on STIR and proton density images and shows no enhancement (fluid intensity) on a T1 fat-sat, post-gadolinium image. On a collection of axial images including proton density, T1 fat-sat, T1 fat-sat, post-gadolinium, and T2 fat-sat images, the mass has fluid intensity and displays no significant enhancement with the exception of a narrow rim of high T2 signal. The mass appears to be displacing rather than invading the muscle tissue.

Differential Diagnosis

Diagnosis

Discussion

Ultrasound-guided soft tissue core biopsy from the slightly enhanced edge confirmed oncologic surgeon’s suspicion of tumor. The leg was amputated above the knee. Images of serial sections show a lesion arising from the tibialis posterior and soleus muscle groups, abutting the tibia. Hemorrhage noted in radiology reports most likely arises from the lesion. Gross findings suggested that this lesion was a sarcoma arising from the deep soft tissues. It also had a histologic pattern associated with vascular lesions, such as angiosarcoma or the less malignant epithelioid hemangioendothelioma. Both of these are distinguished by intracytoplasmic vacuoles, often containing red blood cells. Immunostaining was performed to test the hypothesis that this was a vascular lesion. The cells in this sample were positive for the vascular cell marker CD-31. The actual diagnosis was based on the pattern of growth. Angiosarcoma has a sheet-like pattern of growth, whereas epithelioid hemangioendothelioma has the slightly more differentiated, trabecular pattern seen here. The number of mitoses in these cells indicate malignancy.

Radiology Discussion

Retrospective Discussion of Findings: The periosital reaction was probably the greatest clue to the seriousness of this case. It indicates that the process is chronic. Some of the other indications, such as the slight brightness on T1, can be explained away rather easily if the initial impression suggests a benign process.

Musculoskeletal angiomatous lesions range from benign to malignant. Benign entities include hemangioma, lymphangioma, and glomus tumor. Hemangioendothelioma (HE), hemangiopericytoma (HPC), and angiosarcoma (ASC) have malignant potential. Hemangioendothelioma is a vascular tumor composed of endothelial cells. It can be either benign or malignant. The epithelioid variant is composed of endothelial cells with considerable eosinophilic, often vacuolated, cytoplasm. Malignant epithelioid hemangioepithelioma can occur in osseous or soft tissue. Common osseous locations include the skull, vertebrae, lower extremities.

Typical imaging findings for malignant angiomatous lesions include:

• Radiography: Multifocal lytic lesions ("honeycomb" appearance), aggressive bony destruction with expansion, and soft tissue mass
• Angiography: Intense vascularity with early displacement of peripheral vessels, followed by development of dense blush
• US: Variable appearance (can be either hypo or hyperechoic; Doppler typically shows arteriovenous shunting
• MRI: Prominent serpentine vessels, fluid-fluid levels, contrast enhancement
• T1W: Isointense to muscle; hyperintense with hemorrhage
• T2W: Hyperintense to muscle

Unfortunately, HE, HPC, and ASC cannot be differentiated radologically; nor can they be distinguished from other soft tissue masses if prominent serpentine vessels, which signal a vascular lesion, are not recognized. Malignant tumors of this type do tend to be larger and more aggressive (with infiltration) than benign lesions. They generally lack the fat overgrowth typically found with hemangioma.

Biopsy should be conducted with the assumption that the mass may be a sarcoma. Therefore, an oncologic surgeon should be consulted regarding the appropriate approach. By following this protocol, cross-contamination of areas that would not be resected (should the mass prove malignant) can be avoided. At resection, the entire needle track must be removed.

Angiomatous lesions are treated by resection. If malignant, radiation and chemotherapy may also be applied. Local recurrence is not uncommon, and metastases develop in approximately 20% of cases.

References

Murphey MD: Musculoskeletal Angiomatous Lesions. AFIP Radiologic Pathology Course.

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